 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal.misc;

 import java.util.Vector ;

 /**
  * A string pattern matcher, suppporting "*" and "?" wildcards.
  */
 public class StringMatcher {
     protected String fPattern;

     protected int fLength; // pattern length

     protected boolean fIgnoreWildCards;

     protected boolean fIgnoreCase;

     protected boolean fHasLeadingStar;

     protected boolean fHasTrailingStar;

     protected String fSegments[]; //the given pattern is split into * separated segments

     /* boundary value beyond which we don't need to search in the text */
     protected int fBound = 0;

     protected static final char fSingleWildCard = '\u0000';

     public static class Position {
         int start; //inclusive

         int end; //exclusive

         public Position(int start, int end) {
             this.start = start;
             this.end = end;
         }

         public int getStart() {
             return start;
         }

         public int getEnd() {
             return end;
         }
     }

     /**
      * StringMatcher constructor takes in a String object that is a simple
      * pattern which may contain '*' for 0 and many characters and
      * '?' for exactly one character.
      *
      * Literal '*' and '?' characters must be escaped in the pattern
      * e.g., "\*" means literal "*", etc.
      *
      * Escaping any other character (including the escape character itself),
      * just results in that character in the pattern.
      * e.g., "\a" means "a" and "\\" means "\"
      *
      * If invoking the StringMatcher with string literals in Java, don't forget
      * escape characters are represented by "\\".
      *
      * @param pattern the pattern to match text against
      * @param ignoreCase if true, case is ignored
      * @param ignoreWildCards if true, wild cards and their escape sequences are ignored
      * (everything is taken literally).
      */
     public StringMatcher(String pattern, boolean ignoreCase,
             boolean ignoreWildCards) {
         if (pattern == null) {
             throw new IllegalArgumentException ();
         }
         fIgnoreCase = ignoreCase;
         fIgnoreWildCards = ignoreWildCards;
         fPattern = pattern;
         fLength = pattern.length();

         if (fIgnoreWildCards) {
             parseNoWildCards();
         } else {
             parseWildCards();
         }
     }

     /**
      * Find the first occurrence of the pattern between <code>start</code)(inclusive)
      * and <code>end</code>(exclusive).
      * @param text the String object to search in
      * @param start the starting index of the search range, inclusive
      * @param end the ending index of the search range, exclusive
      * @return an <code>StringMatcher.Position</code> object that keeps the starting
      * (inclusive) and ending positions (exclusive) of the first occurrence of the
      * pattern in the specified range of the text; return null if not found or subtext
      * is empty (start==end). A pair of zeros is returned if pattern is empty string
      * Note that for pattern like "*abc*" with leading and trailing stars, position of "abc"
      * is returned. For a pattern like"*??*" in text "abcdf", (1,3) is returned
      */
     public StringMatcher.Position find(String text, int start, int end) {
         if (text == null) {
             throw new IllegalArgumentException ();
         }

         int tlen = text.length();
         if (start < 0) {
             start = 0;
         }
         if (end > tlen) {
             end = tlen;
         }
         if (end < 0 || start >= end) {
             return null;
         }
         if (fLength == 0) {
             return new Position(start, start);
         }
         if (fIgnoreWildCards) {
             int x = posIn(text, start, end);
             if (x < 0) {
                 return null;
             }
             return new Position(x, x + fLength);
         }

         int segCount = fSegments.length;
         if (segCount == 0) {
             return new Position(start, end);
         }

         int curPos = start;
         int matchStart = -1;
         int i;
         for (i = 0; i < segCount && curPos < end; ++i) {
             String current = fSegments[i];
             int nextMatch = regExpPosIn(text, curPos, end, current);
             if (nextMatch < 0) {
                 return null;
             }
             if (i == 0) {
                 matchStart = nextMatch;
             }
             curPos = nextMatch + current.length();
         }
         if (i < segCount) {
             return null;
         }
         return new Position(matchStart, curPos);
     }

     /**
      * match the given <code>text</code> with the pattern
      * @return true if matched otherwise false
      * @param text a String object
      */
     public boolean match(String text) {
         if(text == null) {
             return false;
         }
         return match(text, 0, text.length());
     }

     /**
      * Given the starting (inclusive) and the ending (exclusive) positions in the
      * <code>text</code>, determine if the given substring matches with aPattern
      * @return true if the specified portion of the text matches the pattern
      * @param text a String object that contains the substring to match
      * @param start marks the starting position (inclusive) of the substring
      * @param end marks the ending index (exclusive) of the substring
      */
     public boolean match(String text, int start, int end) {
         if (null == text) {
             throw new IllegalArgumentException ();
         }

         if (start > end) {
             return false;
         }

         if (fIgnoreWildCards) {
             return (end - start == fLength)
                     && fPattern.regionMatches(fIgnoreCase, 0, text, start,
                             fLength);
         }
         int segCount = fSegments.length;
         if (segCount == 0 && (fHasLeadingStar || fHasTrailingStar)) {
             return true;
         }
         if (start == end) {
             return fLength == 0;
         }
         if (fLength == 0) {
             return start == end;
         }

         int tlen = text.length();
         if (start < 0) {
             start = 0;
         }
         if (end > tlen) {
             end = tlen;
         }

         int tCurPos = start;
         int bound = end - fBound;
         if (bound < 0) {
             return false;
         }
         int i = 0;
         String current = fSegments[i];
         int segLength = current.length();

         /* process first segment */
         if (!fHasLeadingStar) {
             if (!regExpRegionMatches(text, start, current, 0, segLength)) {
                 return false;
             } else {
                 ++i;
                 tCurPos = tCurPos + segLength;
             }
         }
         if ((fSegments.length == 1) && (!fHasLeadingStar)
                 && (!fHasTrailingStar)) {
             // only one segment to match, no wildcards specified
 return tCurPos == end;
         }
         /* process middle segments */
         while (i < segCount) {
             current = fSegments[i];
             int currentMatch;
             int k = current.indexOf(fSingleWildCard);
             if (k < 0) {
                 currentMatch = textPosIn(text, tCurPos, end, current);
                 if (currentMatch < 0) {
                     return false;
                 }
             } else {
                 currentMatch = regExpPosIn(text, tCurPos, end, current);
                 if (currentMatch < 0) {
                     return false;
                 }
             }
             tCurPos = currentMatch + current.length();
             i++;
         }

         /* process final segment */
         if (!fHasTrailingStar && tCurPos != end) {
             int clen = current.length();
             return regExpRegionMatches(text, end - clen, current, 0, clen);
         }
         return i == segCount;
     }

     /**
      * This method parses the given pattern into segments seperated by wildcard '*' characters.
      * Since wildcards are not being used in this case, the pattern consists of a single segment.
      */
     private void parseNoWildCards() {
         fSegments = new String [1];
         fSegments[0] = fPattern;
         fBound = fLength;
     }

     /**
      * Parses the given pattern into segments seperated by wildcard '*' characters.
      * @param p, a String object that is a simple regular expression with '*' and/or '?'
      */
     private void parseWildCards() {
         if (fPattern.startsWith("*")) { //$NON-NLS-1$
 fHasLeadingStar = true;
         }
         if (fPattern.endsWith("*")) {//$NON-NLS-1$
 /* make sure it's not an escaped wildcard */
             if (fLength > 1 && fPattern.charAt(fLength - 2) != '\\') {
                 fHasTrailingStar = true;
             }
         }

         Vector temp = new Vector ();

         int pos = 0;
         StringBuffer buf = new StringBuffer ();
         while (pos < fLength) {
             char c = fPattern.charAt(pos++);
             switch (c) {
             case '\\':
                 if (pos >= fLength) {
                     buf.append(c);
                 } else {
                     char next = fPattern.charAt(pos++);
                     /* if it's an escape sequence */
                     if (next == '*' || next == '?' || next == '\\') {
                         buf.append(next);
                     } else {
                         /* not an escape sequence, just insert literally */
                         buf.append(c);
                         buf.append(next);
                     }
                 }
                 break;
             case '*':
                 if (buf.length() > 0) {
                     /* new segment */
                     temp.addElement(buf.toString());
                     fBound += buf.length();
                     buf.setLength(0);
                 }
                 break;
             case '?':
                 /* append special character representing single match wildcard */
                 buf.append(fSingleWildCard);
                 break;
             default:
                 buf.append(c);
             }
         }

         /* add last buffer to segment list */
         if (buf.length() > 0) {
             temp.addElement(buf.toString());
             fBound += buf.length();
         }

         fSegments = new String [temp.size()];
         temp.copyInto(fSegments);
     }

     /**
      * @param text a string which contains no wildcard
      * @param start the starting index in the text for search, inclusive
      * @param end the stopping point of search, exclusive
      * @return the starting index in the text of the pattern , or -1 if not found
      */
     protected int posIn(String text, int start, int end) {//no wild card in pattern
 int max = end - fLength;

         if (!fIgnoreCase) {
             int i = text.indexOf(fPattern, start);
             if (i == -1 || i > max) {
                 return -1;
             }
             return i;
         }

         for (int i = start; i <= max; ++i) {
             if (text.regionMatches(true, i, fPattern, 0, fLength)) {
                 return i;
             }
         }

         return -1;
     }

     /**
      * @param text a simple regular expression that may only contain '?'(s)
      * @param start the starting index in the text for search, inclusive
      * @param end the stopping point of search, exclusive
      * @param p a simple regular expression that may contains '?'
      * @return the starting index in the text of the pattern , or -1 if not found
      */
     protected int regExpPosIn(String text, int start, int end, String p) {
         int plen = p.length();

         int max = end - plen;
         for (int i = start; i <= max; ++i) {
             if (regExpRegionMatches(text, i, p, 0, plen)) {
                 return i;
             }
         }
         return -1;
     }

     /**
      *
      * @return boolean
      * @param text a String to match
      * @param start int that indicates the starting index of match, inclusive
      * @param end</code> int that indicates the ending index of match, exclusive
      * @param p String, String, a simple regular expression that may contain '?'
      * @param ignoreCase boolean indicating wether code>p</code> is case sensitive
      */
     protected boolean regExpRegionMatches(String text, int tStart, String p,
             int pStart, int plen) {
         while (plen-- > 0) {
             char tchar = text.charAt(tStart++);
             char pchar = p.charAt(pStart++);

             /* process wild cards */
             if (!fIgnoreWildCards) {
                 /* skip single wild cards */
                 if (pchar == fSingleWildCard) {
                     continue;
                 }
             }
             if (pchar == tchar) {
                 continue;
             }
             if (fIgnoreCase) {
                 if (Character.toUpperCase(tchar) == Character
                         .toUpperCase(pchar)) {
                     continue;
                 }
                 // comparing after converting to upper case doesn't handle all cases;
 // also compare after converting to lower case
 if (Character.toLowerCase(tchar) == Character
                         .toLowerCase(pchar)) {
                     continue;
                 }
             }
             return false;
         }
         return true;
     }

     /**
      * @param text the string to match
      * @param start the starting index in the text for search, inclusive
      * @param end the stopping point of search, exclusive
      * @param p a pattern string that has no wildcard
      * @return the starting index in the text of the pattern , or -1 if not found
      */
     protected int textPosIn(String text, int start, int end, String p) {

         int plen = p.length();
         int max = end - plen;

         if (!fIgnoreCase) {
             int i = text.indexOf(p, start);
             if (i == -1 || i > max) {
                 return -1;
             }
             return i;
         }

         for (int i = start; i <= max; ++i) {
             if (text.regionMatches(true, i, p, 0, plen)) {
                 return i;
             }
         }

         return -1;
     }
 }

